Off road vehicles for construction or general commercial applications encounter rigorous service requirements. The tires for such vehicles are required to accommodate high loads and exposure to large amounts of debris, hard packed soil conditions and adverse operating conditions. The vehicles to which the tires are mounted may be large earthmovers that must traverse gravel, broken concrete, or hard packed dirt in the course of normal service duty. It is desirable, therefore, for the tires of such vehicles to be self-cleaning.
The tread region in tires for such applications must have a large height difference between the top and bottom of lugs to provide the necessary traction. A typical tire size may be an 875/65R29, referred to herein as a “65 Series” tire. This tire when produced in a radial construction will have a carcass with a plurality of plies and of belt reinforcement. The tire operates at a relatively high inflation pressure in order to accommodate the load requirements.
Heretofore, the tire industry has attempted to service the industrial/construction/OTR segment of the market with extremely high traction requirements by the placement of agricultural tires in such applications. U.S. Pat. No. 6,263,933 B1, incorporated by reference herein, discloses such an agricultural tire. The tire has a tread package that provides a relatively low Net-to-gross Ratio. While such agricultural tires are adequate from a traction perspective, they are not robust enough to withstand the loads at speeds necessary in the industrial/construction OTR applications.
Available OTR tires have constructions that, while robust enough to handle the loads and speeds necessary in the industrial construction/OTR applications, typically have a tread pattern with a substantially higher net-to-gross ratio for the loads and speeds encountered. Additionally, conventional OTR tires that are typically sized with an aspect ratio in the 85% to 100% range and widebase OTR tires that are typically sized with an aspect ratio in the 75% to 85% range, do not provide adequate flotation and traction for such applications.
Moreover, OTR tires, as opposed to over the highway tires or agricultural tires, generally are available in aspect ratios over 70%. There are relatively few sizes currently available to the industry in aspect ratios of 65% or below.
Accordingly, there has been an ongoing need for an OTR tire that provides a low net-to-gross tread pattern in construction/industrial/OTR applications on relatively low aspect ratio OTR tires. An adequately low net-to-gross ratio allows the tire to be self-cleaning so as to satisfactorily perform in the work environment described above.